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- Title
Two-component Kramers restricted complete active space self-consistent field method with relativistic effective core potential revisited: theory, implementation, and applications to spin-orbit splitting of lower p-block atoms.
- Authors
Kim, Inkoo; Lee, Yoon Sup
- Abstract
The relativistic two-component complete active space self-consistent field theory in Kramers restricted formalism (KRCASSCF) through the framework of the spin-orbit relativistic effective core potential is implemented into the KPACK package. This paper continues the development previously reported [Y. S. Kim and Y. S. Lee, J. Chem. Phys. 119, 12169 (2003)] and extends the theory by means of adding time-reversal symmetry into the relevant expressions so as to complete the course of theoretical development. We retained the usage of elementary spinor excitation operator for defining the spinor rotation operator and derived the gradient and Hessian in simpler forms than previously found. To eliminate redundant computation resulting from repeating sums in the derivatives, a suitable decomposition method is proposed, which also facilitates the implementation. The two-step near second-order approach is employed for convergence. The present implementation is applicable for both closed- and open-shell systems and is used to calculate the atoms of lower p-block. The results for 5p and 6p are in good agreement with the experiments, and those for 7p are comparable to multi-reference configuration interaction results, showing that KRCASSCF is a versatile tool for the relativistic electronic structure calculation of molecules containing moderate-weight through superheavy elements.
- Publication
The Journal of chemical physics, 2013, Vol 139, Issue 13, p134115
- ISSN
1089-7690
- Publication type
Journal Article
- DOI
10.1063/1.4822426